ProjectSummary/Abstract Thegoalofthisresearchistoinvestigateanovelinterventiontoimproveratioreasoninginchildrenwith DevelopmentalDyscalculia(DD).DDisamathematicallearningdisorderthatimpairscalculationabilityand ratioreasoning.Ratioreasoningisanimportantpredictorofadvancedmathskills,aboveevenearlycalculation ability.ChildrenwithDDhavedifficultyparsingnumbersymbolsinratiooperations,butmanyofthesechildren haveanintactnumbersense,calledtheApproximateNumberSystem(ANS).TheANSallowschildren,adults, andnon-humananimalstoapproximatelyandnon-symbolicallysolvemathproblems.Aschildrenadvancein theirmathematicalunderstanding,theyconnecttheirANSrepresentationsofnumberandnumberoperations totheculturallyinventedsymbolicnumeralform.Thisproposalwilltestthenovelhypothesisthatforchildren withDD,practicewithratioreasoningtaskspresentednon-symbolicallywithdotarrayswillfacilitatesymbolic ratioreasoningperformance.Specifically,Ipredictthatthemechanismofthisimprovementwillbeareduction inincorrectstrategyuseduringsymbolicratiocomparison.Totestthesehypotheses,Iwillrecruit9to11-year- oldchildrenwithtypicallydevelopingmathskill(N=62)andchildrenwithpersistentlowmathskillsatriskfor DD(N=62).Iwill1)confirmthattheANSisinvolvedinsolvingnon-symbolicratioproblemsforbothtypically developingchildrenandchildrenatriskforDD,andtestthehypothesesthatchildrenwithDDhaveaweaker relationbetweentheirnon-symbolicandsymbolicratioreasoningabilitythantheirtypicallydevelopingpeers, andthatnon-symbolicratioreasoningskillmoderatestherelationbetweenANSacuityandsymbolicmathskill. 2)Iwillthenassesstherelativeeffectivenessofsymbolicandnon-symbolicratiotrainingonimproving children?sratioskill.Fortypicallydevelopingchildren,practicewithsymbolicmathskillsisthemosteffective waytoimprovesymbolicmathskills.ButforchildrenwithDD,practicesolvinganon-symbolicrepresentation ofaratioproblemmaybemoresuccessfulinfacilitatingsymbolicratioperformance.Finally,3)Iwillexplore whetherimprovedperformanceonthesymbolicratioreasoningpost-testwasduetoareductioninincorrect strategyuse.Aschildrenprogressintheirunderstandingofratios,theygothroughstagesofratiocomparison. Youngchildreninitiallyperformaonedimensionalintegerbasedcomparison,andthenprogresstoafullratio comparisonintegratingboththenumeratoranddenominatoroftheratio.Wehavefoundthatchildrenareless biasedtowardincorrectratiostrategieswithanon-symbolicpresentation.Facilitatingagreaterconnection betweensymbolicandnon-symbolicratioforchildrenwithDDmaythusallowchildrentoconnectthecorrect solutiondevelopedduringnon-symbolicratiocomparisontothesameproblempresentedwithnumber symbols.Resultsofthisresearchwilllaythegroundworkforanoveltypeofinterventiontoremediatethe effectsofDDonchildren?sratioreasoning.